vector<vector<int>> largeGroupPositions(string s) {
	vector<vector<int>> res;
	int n = s.size(), count = 1;
	char t = s[0];
	for (int i = 1; i < n + 1; i++) {
		if (s[i] != t) {
			t = s[i];
			if (count >= 3) {
				res.push_back({i - count, i - 1});
			}
			count = 1;
		} else
			count++;
	}
	return res;
}